Field of Invention
The present invention relates to a field of circuit design, and in particular, to an AC (alternating current)-DC (direct current) conversion circuit.
Description of Prior Art
Along with social development, people use a variety of electronic equipments to satisfy personal needs. Because some electronic equipment of the electronic equipments work with DC current is more stable, a design of AC-DC conversion circuit inside the electronic equipment becomes a key factor for making the electronic equipment work in a stable condition.
FIG. 1 is a diagram of a conventional AC-DC conversion circuit, where 11 indicates an inputting module, 12 indicates a rectifying module, 13 indicates a controlling module, 14 indicates a transforming module, and 15 indicates an outputting module. The rectifying module 12 could properly transform an AC current from the inputting module 11 to be a DC voltage, then the AC-DC conversion circuit could properly control the DC voltage outputting from the rectifying module 12 with a controlling chip U1 of the controlling module 13 to let the transforming module 14 perform the transforming process. Finally, the outputting module 15 outputs a corresponding DC voltage.
However, a filtering capacitor CP8 or a transistor Q23 may be burn out when an input voltage of the inputting module 11 is too high. An output voltage of the outputting module 15 might be unstable when the input voltage of the inputting module 11 is too low.
Therefore, the conventional AC-DC conversion circuit is need to solve the existing problem.